Jacks and applications thereof



Dec. 16, 1969 I L. mow-r 3 JACKS AND APPLICATIONS THEREOF Filed May 17, 1968 2 Sheets-Sheet l Dec. 16, L. o o-r JACKS AND APPLICATIONS THEREOF Filed May 17, 1968 2 Sheets-Sheet 2 United States Patent 3,483,797 JACKS AND APPLICATIONS THEREOF lLucien Diolot, Neuilly, France, assignor to Soeiete Nouvelle Spidem, Paris, France, a corporation of France Filed May 17, 1968, Ser. No. 729,963 Claims priority, application France, May 22, 1967,

Int. Cl. F1511 21702, /18, 7/06 US. Cl. 915 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates to improvements in jacks and discloses a further advance in the art of known jacks, such as e.g. that shown in my earlier Patent No. 3,277,794, which is also assigned to the assignee of this invention.

Known jacks are of two types, i.e. single acting and double acting. In the former kind driving pressure is exerted on only one of the faces of the piston, whereas in the latter type pressure is exerted on oppositely disposed faces of the piston. In each of these types of jacks, the end of the working chamber is integral with the cylinder of the jack and thus is subjected to the effects of the pressure to the same extent as the walls of the cylinder.

The present invention relates to a jack which, as contrasted with existing jacks, affords a number of advantages stemming from the fact that the end of the working chamber is no longer fast with the corresponding end of the jack cylinder, but can slide within the latter, under the action of a judiciously applied auxiliary pressure.

The arrangement of the jack according to the invention and the various advantages which it affords relative to known jacks will be described hereinafter with reference at first being made to a general form of an embodiment and then to a more particular application of the invention as applied to a clamping cylinder for rolling mills.

According to the present teaching there are arranged within a cylinder at least a pair of pistons that are axially movable relative to each other. One piston is provided with an enlarged area which functions as a wall for a chamber and a closure plate for the cylinder forms another wall for the chamber which is filled with a fluid of a predetermined value during operation. Complementally formed portions of the cylinder and piston limit movement of the piston relative to the cylinder.

The aforesaid piston provided with the enlarged area is denoted hereinafter as the working piston and as pointed out, the enlarged surface area is arranged to move relative to the base portion and these surfaces thus form therebetween a precompression chamber.

It will be better understood as the description progress-es that the pressures chosen to be applied against the surface areas of the first and second pistons are of significantly different values. The pressure in the precompression chamber is of a distinctly greater value than that which is introduced to the oppositely disposed surfaces of the several pistons with certain pressure responsive signal means being subjected to the pressure between the pistons and associated with a valve control means that is in operative relation with the precompression chamber.

Thus, it will be understood that as long as the jack is not subjected to any abnormal stress, operation will be effected as with an ordinary jack, i.e. the oppositely disposed surface of the second piston will act as a fixed end. But, should an accidental over-pressure occur, which nat urally would disturb an eflicient operation or possibly cause damage or fracture to the mechanism, a detecting element or other pressure responsive signal means, whose sensitivity and consequently response time has been suitably determined, emits a suitable signal. However, instead of using the emitted signal to cause the rapid discharge of the fluid situated in the working chamber, this signal causes instantaneous emptying of the precompression chamber.

The foregoing discloses the essential features of the jack according to the invention and the attendant advantages resulting therefrom.

In fact, the said precompression chamber can be instantaneously connected to the atmosphere by means of an ultra-rapid valve with a large opening, such as, for example, that described in US. Patent No. 3,277,794, mentioned hereinbefore, when, as is the case with the latter valve, all the control mechanism is directly fixed on the wall of the cylinder, the effectiveness of the valve is further increased owing to the over-pressure in the piping which may be present, causing pressure losses and thus slowing the discharge of the fluid.

The said piping constitutes, on the other hand, more particularly owing to the connections which they comprise, as many risks of leakages in the system.

It will also be seen that, in the jack according to the invention, the discharge of the precompression chamber is effected markedly more quickly since as soon as the valve referred to above opens, the second piston is driven towards the end of the precompression chamber by the action of the over-pressure prevailing in the working chamber, which adds its action to that of the initial pressure of the auxiliary fluid for discharging the said chamber.

Thus, complete independence is achieved between the circuit for supplying the jack with Working fluid, with regulation limitations which such a circuit inevitably comprises, and the safety circuit which, being separate and independent, has its own fluid supply, not interfering in any way with the working fluid circuit.

One distinct advantage of the jack according to the invention is that it will permit the working piston to benefit from a considerable safety travel without disturbing the rigidity of the assembly, thus freeing itself of the effects of the compressibility of the working fluid.

Another advantage of the jack according to the invention is that, with the pressure of the fluid in the precompression chamber optionally available, it is possible instantaneously to connect the chamber with the atmosphere even in the absence of any action of the safety system previously described; for this, in fact, all that has to be done is to deliberately initiate the opening of the safety valve, either manually or automatically, under the action of any appropriate device, completely independent of that provided on the working fluid supply circuit.

Still another advantage of the jack according to the invention is that once the precompression chamber is emptied, it is possible to continue using the jack for a limited amount of time, for example, until the complete apparatus is returned to normal, taking precaution, of course, that overloads do not occur during such operation.

Yet another advantage of the jack according to the invention is that after some incident has caused the emptying of the precompression chamber there is no need, as in the case of conventional systems, to again drain the system conduits before placing it back into service, thus obviating losses of time which are often considerable.

Other objects and advantages will become apparent from a reading of the following specification taken in conjunction with the drawings, in which:

FIG. 1 shows in vertical cross-section a single-acting jack according to the invention; and

FIG. 2 shows generally in vertical cross-section a clamping cylinder for a rolling mill, constituting one application of the jack according to the invention.

Turning now to the drawings, FIG. 1 shows a simplified adaptation of the invention with a single acting jack and a projecting piston; however, it is to be understood that the invention taught herein applies equally as well to double-acting rod-type jacks.

The jack cylinder 4, wherein three bores are formed, each of which increases in size towards one end of the cylinder, forms successively housings for the working piston 6, the precompression piston 5 and the closure plate 8 of the cylinder.

The conduit 12 is adapted to introduce a fluid into the working chamber formed between the oppositely disposed faces of the first and second pistons 5 and 6, respectively.

At 19 is shown the pressure sensitive responsive means or detecting device which is connected to the conduit 12 that extends into the bore provided in the wall of cylinder 4.

As shown in both FIGS. 1 and 2, the first piston 5 is provided with a shoulder which is arranged to abut against a corresponding complementally formed portion of the bore provided in the cylinder 4.

Auxiliary fluid is admitted through an inlet orinfice 26 into the precompression chamber 14 by means of the conduit which extends to the supply 24.

The ultra-rapid full-opening valve 16 intended to connect the chamber to the atmosphere is denoted in FIG. 1 merely by an arrow but a further detailed description of the actual operating mechanism will be later described in connection with FIG. 2.

The jack operates as follows:

Initially, auxiliary fluid is emitted into chamber 14 and the fluid is then maintain during the entire operation at a value very markedly higher than that of the working pressure which, by way of conduit 12, is admitted into the chamber 10 between the opposed pistons 5 and 6, respectively. From this instant, the jack is operated as a conventional jack, irrespective of type.

In the event of excessive pressure, the pressure responsive signal means 19 acts instantaneously to cause the opening of the valve 16 and consequently to bring about an immediate decompression of the system so as to eliminate any danger or damaging fracture.

Operation of the device, however, may be continued for a limited time after excess pressure is noted, despite the safety device being put out of service, but only by taking care to provide precautions against any accidental exceeding of the maximum permitted pressure.

Reference at this time is made to the alternate embodiment shown in FIG. 2 which discloses a clamping cylinder for a rolling mill and constitutes another application of the improved jack according to the invention.

In this embodiment of the invention, it will be seen that the piston 6 comprises a rear portion of reduced diameter which is permitted to slide into or telescope the corresponding bore formed coaxially in the piston 5. This is a device whereby suitable guiding can be ensured for the piston 6 where a low height of the cylinder 4 is utilized.

Further, it is to be understood that the clamping cylinder rests on the lower portion 1 of the upright of a rolling mill housing.

The chock depicted at 2 is provided with a lining 3 which is adapted to bear against the piston 6 of the clamping cylinder.

Basically, the clamping cylinder of FIG. 2 comprises the same parts as that shown in FIG. 1.

At this time a description will be given in greater detail of the additional means which are added to the jack according to the invention as required to practice the particular application with which the description of the second embodiment is concerned.

At 7 there is shown a specially treated metal plate which is formed of a highly compacted or denser material which is availed of where the base portion 8 is constructed of cast iron or other cheap material and may be assembled in the chamber in any suitable manner.

Various sealing rings, such as 9, 9a, 9b, 9c, 9d, 9e, are arranged on the peripheries of the two bores of the cylinder 4 as shown and at 9f there is provided a sealing ring which is situated adjacent the edge of the plate 7 and the complemental shoulder 9g which is provided on the cylinder 4. Also, as shown in FIG. 2, fluid is arranged to travel through the channel 10, then into the axial grooves 13 to ensure permanent communication between channel 10 and the transversely extending fluidized area 11. In the preferred form of this concept of the invention fluidized channel 10 is of annular form.

The cylinder 4- is bored at 15 and provided at its outer terminal wall with a safety valve 16.

The mechanism denoted generally at 17 for releasing and re-engaging the valve has been previously referred to herein as being shown in US. Patent No. 3,277,794.

The reference numeral 18 denotes only one of the plurality of vents which are formed in the wall of the cylinder 4 to permit discharge of any air which may become entrapped within the cylinder when the piston S is raised to the position shown in FIG. 2.

Numeral 20 is, for example, the electromagnetic valve forming part of the system described in the aforesaid patent and permitting the instantaneous opening of the valve 16 in the event such is required.

Generally indicated at 21 is a hydromechanical clamping device typical of those used in rolling mills which act on the volume of the fluid imprisoned with such a device and permit, more particularly, regulating the spacing desired between the rolls of the rolling mill with all necessary precision.

A pump 23 is adapted to supply the precompression chamber 14 by drawing fluid from a reservoir or sump 24 and passing it through line 22 to said chamber. It will be apparent that other means, such as a pressure fluid distribution network, can be made available for use in lieu of the system described.

The operation of this second embodiment is, generally speaking, identical to that described for the jack shown in FIG. 1. The critical pressure in this case is the pressure admissible and envisaged during the course of the rolling operation. Also, it will be apparent that it is permissible to carry out all desired adjustments in a manner completely independent of the operation of the safety system by means of the two clamping cylinders provided on the rolling mill, whether it is at the beginning or during a rolling operation.

The increased travel of the jack according to the present invention constitutes a particularly advantageous arrangement for use in rolling mills. The same applies as regards the improvement of guiding the piston 6 in its cylinder by the means shown.

It will also be appreciated that all risks of fracturing parts are eliminated and also the possibility of continuing an operation once it has been undertaken, despite release following an accidental over-pressure, is of very great advantage in rolling mill operations.

It will also be understood that a practical means is now made available for instantaneously discontinuing contact between the rolling mill rolls and the rolled product, which is always important in the event of e.g. hot rolling of sheets or strip.

It is contemplated also that according to this invention many other applications for use of this improved jack are now made possible and will be readily appreciated by those skilled in this art upon a perusal of this disclosure.

Although two embodiments of the invention have been depicted and described, it will be apparent that these embodiments are illustrative in nature and that a number of modifications in the apparatus and variations in its end use may be effected without departing from the spirit or scope of the invention as defined in the appended claims.

That which is claimed is:

1. A fluid operated jack comprising a cylinder provided with a base portion forming one Wall of a chamber, a first piston means, said piston means including a portion forming another wall of the chamber, said piston further arranged to be normally supported above the base portion of the cylinder by a pressure medium of predetermined value introduced into said chamber, a second piston in said cylinder means arranged to introduce a pressure of lesser value than said first-named pressure between the first and second piston means to actuate the latter and pressure responsive signal means, said pressure responsive signal means adapted to detect excessive force on said second piston and reduce the pressure in said chamber.

2. A fluid operated jack as claimed in claim 1, wherein the cylinder and first piston are formed with complemental shoulder means to limit axial movement of said piston.

3. A fluid operated jack as claimed in claim. 2, wherein said cylinder includes atmospheric vent means, said vent means terminating substantially in the area adjacent to said shoulder means provided between the cylinder and piston means.

4. A fluid operated jack as claimed in claim 1, wherein the first and second piston means are arranged with telescoped portions.

5. A fluid operated jack as claimed in claim 1, wherein seal means are spacedly arranged between the cylinder and said first and second piston means.

6. A fluid operated jack as claimed in claim 1, wherein said pressure responsive signal means includes a valve means.

7. A fluid operated jack as claimed in claim 1, wherein the pressure responsive signal means includes secondary control means, said secondary control means arranged to actuate a valve means.

8. A fluid operated jack as claimed in claim 2, wherein seal means are spacedly arranged between the cylinder and said first and second piston means.

9. A fluid operated jack as claimed in claim 1, wherein an impervious metal plate is associated with said base portion.

10. A fluid operated jack according to claim 1, wherein the first piston means constitutes the clamping means for the stand of a rolling mill.

11. A fluid operated jack according to claim 1, wherein a discharge conduit connects the end section of the working chamber at the side opposite from that occupied by the working piston with the atmosphere.

References Cited UNITED STATES PATENTS 8/1966 Vuichard 51 XR 8/1966 Bollar.

US. Cl. X.R. 605 1, 52, 54.5

It 1 's certified that error appears in the above-identified patent and that: amid Letters Patent are hertby lIOT-IIZC'IIOCI as shown below:

In c010 3, line 33, rinfice" shnuld read rifice--; line 43, "maintain" should read --maintained-; col. 5, line 19, between "cylinder" and "means" a comma should be inserted SIGNED AND SEALED MAY 1 21970 (SEAL) Attest:

WILLIAM E. 50mm, .m.

Attasting Officer 

